Conventional gas fires of the zero-clearance type include an internal combustion chamber where the gas is burned in a combustion assembly which includes elements simulating burning materials to provide an attractive appearance. The combustion chamber includes side walls, top wall, bottom wall and a rear wall.
The combustion chamber is mounted within a housing which separates the combustion chamber from exterior building components so that the housing defines a top wall, a rear wall, a bottom and sides which support the combustion chamber and define heat exchange spaces for the passage of air to maintain the exterior housing cool while the combustion chamber is heated. In most cases this is achieved without the use of insulation materials by providing the required spacing and the required air flow to extract sufficient heat to maintain the exterior housing at the required low temperature.
The combustion chamber may be of the type which draws in combustion air through a duct exterior to the building to be heated and expels the combustion products through another duct also exterior to the building. In some cases these ducts are arranged one inside the other to provide a convenient communication of the airflow and flue gas flow while also acting to transfer heat therebetween. In other cases the combustion air is drawn in from the interior of the building and only the combustion products pass to the exterior of the building for discharge. In yet further cases the arrangement is vent free so that the air for combustion is drawn from the room and the combustion products are returned to the room without any external vents. Where combustion air is drawn from the room, this may enter through a front opening or it may be drawn upwardly through the base of the combustion chamber from the underlying housing portion. The arrangement of the present invention can be utilized with any of these types of construction.
In order to heat the interior of the building, it is common that an air circulating path is arranged around the combustion chamber with air entering at the bottom of the combustion chamber between the bottom of the combustion chamber and the bottom of the housing, and passes along the rear of the combustion chamber and over the top of the combustion chamber to a discharge between the top of the combustion chamber and the top of the housing. In addition some air may be returned along the sides through suitable vent openings. This arrangement is particularly effective in extracting the heat from the combustion chamber and transferring it into the interior of the building.
Commonly the opening at the bottom of the housing underneath the combustion chamber is covered by a vertical panel defining a series of louver openings allowing the air to enter into the opening while providing an attractive appearance. Similarly the top opening above the combustion chamber is also covered by a panel defining louver openings for the passage of the discharge air.
The front of the combustion chamber is closed by a transparent panel in the direct vent type where combustion air is drawn from the exterior through a suitable exterior vent into a closed combustion chamber. However the front may be open in the vent-free type where air is drawn into and discharged from the combustion chamber into the room. In the vented type where combustion air is drawn from the room but vented to the exterior, the front is generally closed by a transparent cover panel but it does not have to be.
These arrangements are commonly used and the air exchange path which passes from the bottom up the rear and over the top has been very successful since it optimizes the airflow system and provides the best transfer of heat from the combustion chamber to the room to be heated.
There is however a desire to provide an arrangement of fire place which omits the louver openings and thus allows only the open front face of the combustion chamber to be visible at the front of the fireplace. This is considered in some cases to be more attractive since there are no visible louver panels and only the combustion chamber with the attractive burning combustion system is visible at the front face.
In U.S. Pat. No. 5,626,127 there is disclosed an arrangement of this type. This provides on the front face of the housing a surrounding panel defining a top panel portion above the combustion chamber and a bottom panel portion below the combustion chamber. These can be covered by decorative materials so that the only part of the fire place visible is the combustion chamber itself.
In this arrangement the recirculating airflow which acts to extract heat from the combustion chamber and transfer it into the room to be heated acts only at the bottom of the combustion chamber so that air is drawn over the top edge of the bottom panel underneath the combustion chamber through central horizontal openings and is discharged through side ones of the horizontal openings. Thus the air enters the area underneath the combustion chamber, turns through a 1800 and passes back out from underneath the combustion chamber.
The present inventor has realized that this arrangement has a number of disadvantages. Firstly the heat exchange system is relatively inefficient since it extracts heat from only underneath the combustion chamber. Secondly this construction is entirely different from the conventional fireplace in that it constitutes an alternative model of fireplace different from the conventional louver type construction. The manufacturer therefore must manufacture this arrangement as a separate model from the conventional louver arrangement and thus the distributor must carry a series of further models thus significantly increasing inventory bearing in mind that each model whether it be of the louver type or the non-louver type comes in a number of different sizes and capacities.